1. Field of the Invention
The present invention relates to an apparatus and method for optimizing a non-ejection correction parameter of an ink-jet head, an image recording apparatus and method, a test chart, and an ink-jet printer.
2. Description of the Related Art
When an ink-jet head is used for drawing in an ink-jet recording apparatus for a long period of time, some nozzles come into a non-ejection state due to clogging or breakdown. Particularly in a case of drawing in a single-pass method, the position of a non-ejection nozzle appears as a white stripe, and thus needs to be corrected.
Japanese Patent Application Laid-Open No. 2012-71474 discloses a technique for determining a correction parameter for non-ejection correction that varies with a difference in a landing interference pattern based on an arrangement form of a plurality of nozzles on a head, and correspondence information indicating a correspondence relation between a plurality of types of landing interference patterns and respective nozzles corresponding to a landing interference causing factor including a landing order of ejected droplets defined from a relative movement direction between the head and a recording medium.
In Japanese Patent Application Laid-Open No. 2012-71474, correction parameters for non-ejection correction are referred to based on the positional information of the non-ejection nozzle, and a corrective calculation of input image data using the corresponding correction parameter is performed to generate image data modified so as to compensate for the output of a non-ejection nozzle by use of nozzles other than the non-ejection nozzle.
Accordingly, the non-ejection correction parameter can be obtained in consideration of the influence of landing interference of droplets ejected from the other nozzles around the non-ejection nozzle on the recording medium. Correcting performance is further improved by performing non-ejection correction by use of the parameter.
In Japanese Patent Application Laid-Open No. 2012-71474, it is assumed that “optimum non-ejection correction parameters for the nozzles included in the same group can be considered to be equal to each other”. However, the assumption does not hold true with respect to all the nozzles in actual cases. Variation in the optimum value of the non-ejection correction parameter between respective nozzles is increased depending on, for example, variation in a landing position error of ink ejected from each nozzle between respective nozzles or variation in the amount of ejected ink. If the same parameter is applied to the nozzle group having variation in the optimum value as described above, stripe unevenness is caused due to excess correction or deficient correction.
To solve the problem in Japanese Patent Application Laid-Open No. 2012-71474, individual non-ejection correction parameters for all the nozzles need to be optimized. However, there are a large number of nozzles (thousands to ten thousands) in a single-pass system. A technique for optimizing all the parameters thus needs to be an efficient optimizing method. As the efficiency of the optimizing method is lower, a longer processing time or a larger number of test chart sheets is required.